This invention relates generally to fuel cells and, more particularly, to fluid flow plates configured for promoting fluid service and design flexibility.
Fuel cells electrochemically convert fuels and oxidants to electricity. A Proton Exchange Membrane (hereinafter xe2x80x9cPEMxe2x80x9d) fuel cell converts the chemical energy of fuels such as hydrogen and oxidants such as air/oxygen directly into electrical energy. The PEM is a solid polymer electrolyte that permits the passage of protons (i.e., H+ ions) from the xe2x80x9canodexe2x80x9d side of a fuel cell to the xe2x80x9ccathodexe2x80x9d side of the fuel cell while preventing passage therethrough of reactant fluids (e.g., hydrogen and air/oxygen gases). The direction, from anode to cathode, of flow of protons serves as the basis for labeling an xe2x80x9canodexe2x80x9d side and a xe2x80x9ccathodexe2x80x9d side of every layer in the fuel cell, and in the fuel cell assembly or stack.
In general, an individual PEM-type fuel cell may have multiple, generally transversely extending layers assembled in a longitudinal direction. In a typical fuel cell assembly or stack, all layers which extend to the periphery of the fuel cells have holes therethrough for alignment and formation of fluid manifolds that generally service fluids for the stack. Typically, gaskets seal these holes and cooperate with the longitudinal extents of the layers for completion of the fluid supply manifolds. As may be known in the art, some of the fluid supply manifolds distribute fuel (e.g., hydrogen) and oxidant (e.g., air/oxygen) to, and remove unused fuel and oxidant as well as product water from, fluid flow plates which serve as flow field plates of each fuel cell. Other fluid supply manifolds circulate coolant (e.g., water) for cooling the fuel cell.
In a typical PEM-type fuel cell, the membrane electrode assembly (hereinafter xe2x80x9cMEAxe2x80x9d) is sandwiched between xe2x80x9canodexe2x80x9d and xe2x80x9ccathodexe2x80x9d gas diffusion layers (hereinafter xe2x80x9cGDLsxe2x80x9d) that can be formed from a resilient and conductive material such as carbon fabric or paper. The anode and cathode GDLs serve as electrochemical conductors between catalyzed sites of the PEM and the fuel (e.g., hydrogen) and oxidant (e.g., air/oxygen) which flow in respective xe2x80x9canodexe2x80x9d and xe2x80x9ccathodexe2x80x9d flow channels of respective flow field plates.
Typically, the distribution of reactant gases to the various fluid flow plates in the fuel cell stack, as well as removal of unused reactant gases and water from the plates, is accomplished by the fluid flow manifolds. Each of the various components in the stack has a xe2x80x9cmanifold holexe2x80x9d which, when aligned, form columns that are used as fluid flow manifolds. The fluid flow manifolds conduct their respective fluids substantially perpendicular to the planes of the various fluid flow plates. If a particular plate distributes the fluid that is being conducted through a particular fluid manifold, that manifold must be in communication with that plate""s flow channels.
Accordingly, it is desirable to provide a fluid flow plate which allows fluids to pass from the fluid manifolds directly to the flow channels while providing an adequate seal to prevent leakage of fluids.
The invention provides a fluid flow plate for a fuel cell. The fluid flow plate includes a first face and a fluid manifold opening for receiving a fluid and at least one flow channel defined within the first face for distributing a reactant in the fuel cell. A dive through hole is defined in and extends through the fluid flow plate. The dive through hole is fluidly connected to the fluid manifold opening by an inlet channel, defined within an opposite face of the fluid flow plate. The dive through hole and the inlet channel facilitate transmission of a portion of the fluid to the flow channel. A groove, adapted to receive a sealing member, is also defined within the first face and/or the opposite face. The sealing member may comprise a gasket which seals respective fluid manifolds, thereby preventing leaking of fluid.